Prepare cake mix according to package directions, except replace the water with an equal amount of champagne. Pour batter into prepared pans, spreading evenly. Bake according to package directions. Cool in pans on wire racks for 10 minutes. Remove from pans; cool completely on racks.
Place one cake layer, bottom side up, on a serving plate. Spread with peach jam.
In a large bowl, whip heavy cream until stiff peaks form. Fold in 2 tablespoons of peach jam. Use immediately to frost cooled cake layers. Add a layer of frosting over peach jam layer. Top with remaining cake layer, rounded side up. Use remaining frosting to frost top layer. If desired, top assembled cake with fresh peach slices and a drizzle of honey.